The present invention relates to a front vehicle body structure centering around a cowl front panel disposed in the widthwise direction of a vehicle on a front portion of the vehicle.
In general, in a front vehicle body structure, an engine room and a passenger's room are partitioned by a dash lower panel. A cowl front panel extending in the widthwise direction of a vehicle is joined to an upper portion of the dash lower panel. The cowl front panel supports a lower portion of a front glass at its upper edge portion. A dash upper panel is joined to the cowl front panel to form a closed space. This closed space defines a space where, for example, a duct for guiding air extracted from outer air toward a predetermined air-conditioning system is formed.
As a front vehicle body structure centering around a cowl front panel, a cockpit unit mounting structure for a vehicle is disclosed in Japanese Utility Model Laid-Open No. 64-39179. A glass support portion of a cowl front panel is located either behind or in front of a dash lower panel, as disclosed in the above reference.
A front glass is required to have a large curvature in order to improve an outer appearance or to reduce an air resistance of a vehicle body. In order to support a lower portion of a front glass having a large curvature, two side portions of the glass support portion of the cowl front panel must be bent toward the rear side of the dash lower panel, and a central portion thereof must be bent toward the front side of the dash lower panel. That is, the glass support portion must be worked to match with the curved glass.
However, it is not easy to precisely work one cowl front panel to be bent in different directions. Therefore, the above-mentioned requirement for increasing the curvature of the front glass cannot be satisfactorily met.
Since the cowl front panel is considerably heavy since it has a length corresponding to the vehicle width, as described above. For this reason, workability upon assembly with this cowl front panel poses another problem.
A method of fixing two side portions of a dash upper panel to inner members of corresponding front pillars of a vehicle body by welding is known. In an assembly of respective members in a vehicle body structure, after a dash lower panel is disposed, front pillars (to which hinge pillars have already been joined) are assembled to a vehicle body from side portions of the vehicle body, and then, a cowl front panel and a dash upper panel are joined by welding.
In each front pillar, inner and outer members have already been joined. For this reason, when the dash upper panel is joined to the front pillar inner members, spot welding cannot be performed. Therefore, since fillet welding is performed in place of spot welding, a sufficient joint strength cannot be assured, and rigidity of a vehicle body cannot be improved.
Since the dash upper panel has a length corresponding to the vehicle width and is relatively large and heavy, as described above, its transportation is not easy.
An air inlet port for introducing outer air taken from a separate air intake portion is formed in the cowl front panel when it is located behind a front glass. An air outlet port for sending outer air to a predetermined air-conditioning system is arranged in a bottom-side plate portion of the dash upper panel. Two partition plates are fixed to a portion which corresponds to the air inlet and outlet ports and is present in a space in the dash upper panel. The two partition plates serve as duct-side walls, so that the air inlet and outlet ports communicate with each other in a small space. These partition plates are fixed as follows. That is, a welding margin formed by bending a portion of each partition plate is brought into contact with the inner wall surface of the dash upper panel, and is fixed by, e.g., spot welding.
However, when spot welding is performed while the welding margin is brought into contact with the inner wall surface of the dash upper panel, as described above, one electrode of spot welding must be located on the welding margin of the partition plate located in the dash upper panel, and the other electrode must be located on the outer surface of the dash upper panel. For this reason, it is not easy to automate such welding, resulting in poor warkability in assembly of a duct.